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Is my professor an idiot?

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  • Is my professor an idiot?

    Im taking exercise physiology at my university, and I just got out of class and I'm confused..
    My professor made these three points..
    1) The brain can ONLY function on glucose.
    2) High fat and low carb diet makes you gain fat.
    3) Low carbohydrate diets make you use protein for fuel, thus, deteriorating muscle. Again, she says the body stores the fat because its in "starvation mode".

    Clearly this is 100% against the paleo theme.

    Can I get some sound scientific feedback on this please? Ive been paleo for 6+ months, and when I was living at home this summer, I gained about 6 lbs, reaching 150lb. At this time I had more access to food, and I was eating more vegetables and fruit, consuming near 200g carbs/day. Now Im at school and Im eating 100g carbs/day, 150+g protein, and about 130g fat/day. My weight has gone down to 144lb. Am i losing muscle mass or fat? My body composition looks the same, so Im not sure where the weight loss is from. Help me out here because Im frustrated..

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  • #2
    Also, im 19, 5'10", and eat about 2200+/- calories/day. Workout 3-4 times a week, bodyweight training. Been doing this for 3 yrs.

    Sent from my XT907 using Marks Daily Apple Forum mobile app


    • #3
      The brain does need a bit of glucose, although it can run mostly on ketones, and many argue more efficiently.
      High fat and low carb diets CAN make you gain fat if you can manage to overeat, but many people find it hard to do.
      Low carbohydrate diets do make you use a little protein for fuel, but they tend to be high protein anyway, so muscle catabolism isn't really an issue.

      I recommend you read the most recent post on and look into his citations if you need something from medical journals or whatnot.

      Or, even better, just bite your tongue, get your A, and be ready for the rest of the bad science you'll be forced to regurgitate in order to earn a degree in ex-phys.
      The Champagne of Beards


      • #4
        Well, (1) is definitely not true. The brain can also run on ketones. This is well known. Just look in any biochemistry textbook.

        As for (2) and (3), I think it's contradicted by anecdotal evidence, at least. I don't have any citations to back them up, but I'm sure others can provide you with that.

        My journal


        • #5
          It sounds like she is teaching from a purchased textbook or media sound bites and has no firsthand knowledge about the subject material. Award yourself an A and then answer the questions on the text the way she wants you to, so she will give you a good grade, too.


          • #6
            bummer, I guess I dident loose 50+ on low carb after all.....
            Every time I hear the dirty word 'exercise', I wash my mouth out with chocolate.



            • #7
              Basically +1 to all those that already responded

              And most college level intro courses arent going to talk about the nuances of things. I mean I'm assuming this is an introductory level exercise physiology course. If so then we can cut the professor a bit of slack. If you are in a masters program.... get your money back.

              Bah, never mind. Get your money back either way. 1, 2, and 3 are not supported by any clinical trials to date. In fact I can at least cite a few that go completely against those conclusions.

              1. Is freaking easy. The answer is ketones.
              2. Basically any low carb trial that shows loss of fat refutes that.
              3. Needs more study, but there is more evidence that low carb is lean mass SPARING than not.


              Last edited by Neckhammer; 09-06-2013, 10:44 AM.


              • #8
                Yes. The answer to your question is yes.
                "The soul that does not attempt flight; does not notice its chains."


                • #9
                  Originally posted by TheyCallMeLazarus View Post
                  Yes. The answer to your question is yes.


                  • #10
                    Your professor is mostly correct.

                    1). When ketone bodies are created, they inhibit glucose oxidation to spare glucose to the brain. Ketones themselves are limited by transport capacity.
                    2). You lose fat on VLC, by liberating stored fat, but there can be a rebound effect.
                    3). There can be no way that VLC is lean mass sparing. Protein has a beneficial effect on lean mass preservation. Adequate carbs prevents protein from being used to make glucose. Proteolytic enzymes that digest protein are also inhibited by excess fat.
                    Make America Great Again


                    • #11
                      Oh, Derp, it's so cute when you make up stuff.

                      Any diet that provides enough protein for your body's needs is a "protein-sparing" diet. The idea that eating enough protein but also some undefinable level of fat will lead to your body not using the protein you eat but instead cannibalizing your muscles for amino acids is utter hogwash.

                      When I spent my last stint in college, the exercise physiology students had a "senior projects" display in the gym. The one I recall was where volunteers kept a food diary for a period of time and had their body fat measured. People who consumed less fat had higher body fat.


                      • #12
                        Except I'm not making it up.

                        Oh, boy, that's solid proof right there. After exercise, muscles consume mainly fats, so maintaining relatively large muscles prevents accumulation of fats.
                        Make America Great Again


                        • #13
                          Originally posted by Derpamix View Post
                          Except I'm not making it up.

                          Oh, boy, that's solid proof right there.
                          I would like to see the references you can cite where it says that the body does not use fat for fuel, and preferentially uses protein for fuel. That's what you're claiming. Stop being such an untermench.


                          • #14
                            the body can use fat for fuel to some extent? If you don't even know how substrates interact, there is not much I can do to help you. Read some more books.
                            Make America Great Again


                            • #15
                              1. References to ketones and brain function apply only to people in ketosis, which is less than 25 g carb/day (VLC). Primal recommends at least 50 g/day, 100 long-term, and a little more if you work out. That's no longer ketosis. So even if you're prof is (rightfully?) against ketosis, she still isn't against Primal. Primal and ketosis are NOT the same thing.

                              2. "Fat makes you fat" is a misconception invented by Ancel Keys in the 1970's and hounded through Congress by carb lobbyists, culminating in 1992 with the Diabetes Pyramid. The books of Gary Taubes have a few things to say about Ancel Keys, none of them flattering.

                              3. The prof is assuming that you are already low fat, and that you are now cutting carbs in addition to cutting fat. In which case she's right that only protein is left. The Primal idea of replacing carbs with fat doesn't enter her mind.
                              5'0" female, 45 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained back to 115(!) on SAD chocolate, potato chips, and stress. Currently 111.